1. Field of the Invention
The present invention relates to a real-image finder through which an erect image is viewed.
2. Description of the Related Art
It is known for a real-image finder to have an objective optical system, which forms an inverted real image of an object, that is, upside down and reversed from left to right, to be viewed on a primary image forming plane on which an image by an objective optical system is formed, and on which a field frame is arranged to lie; an ocular optical system through which the object image formed on the primary image forming plane can be observed; and an image erecting optical system which reinvertes the above inverted real image to the proper orientation so that the image with the proper orientation is viewed as an erect image.
In the above mentioned real-image finder, if a foreign matter, such as dust, exists in the vicinity of the field frame, the foreign matter is viewed together with the object image through the ocular optical system. To prevent this, predetermined members for the finder are placed in a predetermined sealed casing. Consequently, foreign matters are prevented from entering the sealed casing, so that the primary image forming plane is in a dust-free environment. However, the above mentioned sealing operations have to be carried out in a dust-free environment such as a clean room. In particular, an increasing number of cameras have been employing LCDs (liquid crystal displays) which have an inherent tendency to attract foreign matter due to static electricity. Accordingly, the possibility of foreign matter sticking to the LCD, i.e., the field frame, during the sealing operations has been increased. Moreover, once the field frame is sealed, it is difficult to adjust the position of the field frame.